The present invention provides a stackable interlocking intervertebral support system, and methods for supporting adjacent vertebrae using a stackable interlocking intervertebral support system.
In preferred aspects, the present invention comprises two, three (or more) separate portions which are stacked together to form an interlocked intervertebral support assembly. Advantageously, two of these three (or more) portions may be identical in size and shape, as will be explained. In the optional aspect of the invention in which only two separate portions are used, these two portions may be identical to one another in size and shape.
In one preferred aspect, the present invention preferably comprises a center portion, a top portion and a bottom portion. The top portion is positioned on top of the center portion and the bottom portion is positioned under the center portion. The top and bottom portions may be identically shaped and dimensioned, but are positioned upside down with respect to one another, on opposite sides of the center portion, as will be explained. In another aspect of the invention, however, only two portions are used, with the top portion being positioned directly on top of the bottom portion (with no center portion(s) required). In further aspects of the present invention, more than three separate portions may be used. In such aspects, a plurality of identically shaped center portions are stacked one on top of the other. In other alternate aspects, various portions (including top, center and bottom portions) may be stacked side by side one another).
In accordance with the present invention, the center portion has a recess in each of its top and bottom surfaces. Each of the top and bottom portions of the present system also have recesses therein which engage and interlock with the recesses in the center portion. More specifically, the top portion preferably has a recess in its bottom surface and the bottom portion has a recess in its top surface which engage the respective recesses in the top and bottom of the center portion.
The present invention is assembled simply by stacking the three portions (top, center & bottom) one on top of one another in a patient's intervertebral space. When stacked together, the present assembly will form an “X” or “cross” type of shape, providing support over a large surface area of the adjacent vertebrae. In further optional aspects of the invention, more than three portions are stacked together one on top of one another in a patient's intervertebral space. Specifically, a plurality of center portions are stacked on a bottom portion and a top portion is stacked thereover.
A further advantage of the present system is that, when assembled, it provides support in two perpendicular directions, thereby supporting a large area of the adjacent vertebrae, yet using only a minimal amount of material in actually achieving this advantage. This advantage is due, at least in part, to the assembled “cross” shape of the assembly. Moreover, the present invention can be dimensioned to be of a size such that the “arms” of the “cross” extend outwardly towards the edges of the vertebrae, providing support over the cortical bone at the vertebral edges.
Another advantage of the present invention is that, as the adjacent vertebrae tend to push together, this will hold the present support assembly together, even in the absence of any mechanical fastening or securing mechanisms between the top, center & bottom portions of the system. Specifically, both (one or more) center portion(s) and the two top/bottom portions are uniquely shaped and dimensioned such that when positioned one on top of another, they will remain firmly together, resisting any lateral tendency to slip apart.
Yet another advantage of the present invention is that it may be easily inserted into a patient's intervertebral space in a bi-portal minimally invasive surgical approach. Specifically, the bottom portion may be inserted through a first cannula into the patient's intervertebral space, with the center portion(s) thereafter being inserted through a second cannula into the patient's intervertebral space. The top portion may then be inserted through the first cannula into the patient's intervertebral space. In this aspect of the invention, the first and second cannulae are generally perpendicular to one another, being positioned in opposite posterolateral approaches. Alternatively, all of the portions of the assembly may be inserted through the same operating cannula into the patient's intervertebral space, with successive portions then rotated perpendicular to one another after they have been positioned in the patient's intervertebral space.
In preferred aspects, each of the center, top and bottom portions of the assembly have a tapered end, which is dimensioned to engage a ramping structure disposed within one of the recesses on an adjacent portion such that the separate portions of the assembly may be “slip-fit” together, with pressure between the adjacent vertebrae holding each of the pieces of the assembly together. In addition, an optional tapered front end of the center portion may be used to pry apart the adjacent vertebrae, prior to positioning the top portion thereover.
In optional aspects of the invention, a plurality of the present support assemblies can be positioned in a patient's intervertebral space, either on top of, beside, or both on top of and beside, one another.